Closed code423n4 closed 2 years ago
This is very similar to #62 and #65
Very similar, but up to the judge to group them
Leaving https://github.com/code-423n4/2022-01-yield-findings/issues/67 valid but marking the rest as invalid as they are duplicates by the same warden
Handle
Dravee
Vulnerability details
Impact
Increased gas cost due to unnecessary automatic underflow checks.
Solidity version 0.8+ comes with implicit overflow and underflow checks on unsigned integers.
When an overflow or an underflow isn't possible (as an example, when a comparison is made before the arithmetic operation, or the operation doesn't depend on user input), some gas can be saved by using an
unchecked
block.https://docs.soliditylang.org/en/v0.8.10/control-structures.html#checked-or-unchecked-arithmetic
Proof of Concept
In
ConvexStakingWrapper.sol:_calcRewardIntegral()
, there's this if/else statement:As you can see on line 245 (@audit-info), there's a substraction that can't underflow, as the only way to get to this line is if
userI < rewardIntegral
. This substraction should get computed inside anunchecked
block and stored in a variable, which would then be used in the checked calculation.Tools Used
VS Code
Recommended Mitigation Steps
Uncheck arithmetic operations when the risk of underflow or overflow is already contained by wrapping them in an
unchecked
block